In a wideband wireless communications system, a signal tends to decrease from frequency selective fading due to multi-path transmissions. An orthogonal frequency division multiplexing (OFDM) system has been proposed to overcome the problem of frequency selective fading by dividing the total bandwidth into a plurality of subcarriers such that each subcarrier bandwidth is sufficiently narrow to enable data modulation symbols to be carried by that subcarrier with relatively flat fading.
The orthogonal frequency division multiple access (OFDMA) system uses an OFDM modulation technique to multiplex the traffic data of a plurality of mobile stations by both frequency and time. In a cellular communication network based on OFDMA, the base station communicates with the mobile stations that are within coverage by using signals that are orthogonal in frequency, and therefore eliminate intra-cell interference. However, some inter-cell interference still exists that comes from the signals of the adjacent base stations as well as the mobile stations within coverage of those base stations; this inter-cell interference degrades network performance in cell coverage as well as system throughput.